Propofol anaesthesia via target controlled infusion or manually controlled infusion: effects on the bispectral index as a measure of anaesthetic depth.

Target controlled infusions (TCI) of propofol allow anaesthetists to target constant blood concentrations and respond promptly to signs of inappropriate anaesthetic depth. Studies comparing propofol TCI with manually controlled infusion (MCI) reported similar control of anaesthesia, but did not use an objective measure of anaesthetic depth. We therefore tested whether the Bispectral Index (BIS), an electroencephalographic (EEG) variable, is more stable during propofol TCI or MCI. Forty patients received midazolam and fentanyl before induction and were randomized to TCI or MCI. Target propofol concentrations in the TCI group were 3 to 8 microg/ml. The MCI group received propofol bolus (approximately 2 mg/kg) and infusion (3 to 10 mg/kg/h). Neuromuscular blockade was achieved with rocuronium. Following endotracheal intubation, nitrous oxide (66%) in oxygen was delivered and propofol infusion and fentanyl boluses were titrated against clinical signs. Blood pressure, heart rate and EEG were recorded, although the anaesthetist was blind to BIS values. The ideal BIS for general anaesthesia was defined as 50. Performance error, absolute performance error, wobble and divergence of BIS, and maximum changes in blood pressure and heart rate were compared using two-sample t-tests or rank-sum tests where appropriate. There was no difference in absolute performance errors during maintenance of anaesthesia with propofol TCI or MCI (23 +/- 11% vs 23 +/- 9%; P=0.97). The two groups did not differ significantly in performance error, wobble, divergence on haemodynamic changes. We conclude that TCI and MCI result in similar depth of anaesthesia and haemodynamic stability when titrated against traditional clinical signs.     

Comparison of manual infusion of propofol and target-controlled infusion: effectiveness, safety and acceptability

BACKGROUND: Diprifusor TCI is a newly developed target-controlled system for the infusion of propofol. Purpose of this study is to evaluate the acceptability, efficacy and safety of Diprifusor TCI in comparison with the manually controlled technique. METHODS: This multicentre, randomised, parallel group study was carried out in 160 patients undergoing surgical procedures of 10 min to 4 h duration in 8 centres. In each centre 20 male or female patients, aged > or = 18 years, ASA I-III were randomised to treatment with either Diprifusor TCI (TCI group--80 patients) or manually controlled infusion (MI group--80 patients). Assessments included hemodynamics; adverse events, including accidents, actual or possible; recovery times; anesthetist ratings of quality of induction and maintenance, and of ease of control and use of technique. Ratings were summed up in a global quality score (study end-point). RESULTS: Induction doses were significantly lower (median values 1.4 vs 1.9 mg/kg) and maintenance infusion rate significantly higher (median values 10.2 vs 8.8 mg/kg/h) in the TCI group; anesthetists ratings obtained maximum scores in most patients of either group, but more frequently in the TCI group, with significant differences for ease of control (good 91.2% TCI vs 74.7% IM; adequate 8.8 vs 21.5%; poor 0 vs 3.8%), and of use of technique (good 91.2% TCI vs 60.8% IM; adequate 8.8 vs 39.2%); the global quality score showed a significant advantage for the TCI system (median value 12 vs 11). CONCLUSIONS: The TCI technique is effective and safe, and has a better acceptability than the manually controlled infusion technique.     

Target-controlled infusion or manually controlled infusion of propofol in high-risk patients with severely reduced left ventricular function

OBJECTIVE: To compare hemodynamics, time to extubation, and costs of target-controlled infusion (TCI) with manually controlled infusion (MCI) of propofol in high-risk cardiac surgery patients. DESIGN: Prospective, randomized. SETTING: Major community university-affiliated hospital. PARTICIPANTS: Twenty patients undergoing first-time implantation of a cardioverter-defibrillator with severely reduced left ventricular function (left ventricular ejection fraction <30%). INTERVENTIONS: Anesthesia was performed using remifentanil, 0.2 to 0.3 microg/kg/min, and propofol. Propofol was used as TCI (plasma target concentration, 2 to 3 microg x mL; n = 10) or MCI (2.5 to 3.5 mg/kg/hr; n = 10). MEASUREMENTS AND MAIN RESULTS: Hemodynamics were measured at 6 data points: T1, before anesthesia; T2, after intubation; T3, after skin incision; T4, after first defibrillation; T5, after third defibrillation; and T6, after extubation. There were no significant hemodynamic differences between the 2 groups. Dobutamine was required to maintain cardiac index >2 L/min/m(2) in significantly more patients of the TCI group than of the MCI group. Mean dose of propofol was higher in the TCI patients (6.0 +/- 1.0 mg/kg/hr) than in the MCI patients (3.0 +/- 0.4 mg/kg/hr) (p < 0.05), whereas doses of remifentanil did not differ. Time to extubation was significantly shorter in the MCI (11.9 +/- 2.4 min) versus the TCI group (15.6 +/- 6.8 min). Costs were significantly lower in MCI patients (34.73 dollars) than in TCI patients (44.76 dollars). CONCLUSIONS: In patients with severely reduced left ventricular function, TCI and MCI of propofol in combination with remifentanil showed similar hemodynamics. TCI patients needed inotropic support more often than MCI-treated patients. Although extubation time was longer in TCI patients and costs were higher, both anesthesia techniques can be recommended for early extubation after implantation of a cardioverter-defibrillator.     

丙泊酚靶控输注和人工控制输注用于颅内动脉瘤介入治疗的比较

目的比较丙泊酚靶控输注（TCI）和人工控制输注（MCI）在颅内动脉瘤介入治疗术中麻醉效果、对呼吸循环功能及不良反应发生的影响。方法20例颅内动脉瘤患者。随机分为两组：M组采用丙泊酚MCI；T组采用丙泊酚TCI。分别记录麻醉效果，诱导与苏醒时间，丙泊酚总用量，监测不同时间点的血压（BP），心率（HR），血氧饱和度（SpO2）。记录术中体动、舌后坠、术后不良反应例数。结果两组患者麻醉与苏醒时间差异无显著性（P〉0．05），丙泊酚总用量T组明显大于M组（P〈0．05），T组麻醉效果优于M组（P〈0．05）。丙泊酚诱导后血压下降程度M组大于T组（P〈0．05），术中出现体动及术后不良反应例数M组多于T组（P〈0．05）。结论丙泊酚靶控输注用于颅内动脉瘤介入治疗优于丙泊酚人工控制输注。     

Target controlled infusion (TCI)--status and clinical perspectives

The technique of target controlled infusion (TCI) has influenced the development of intravenous anaesthesia substantially and opens the possibility of many new and exciting applications in peri-operative anaesthetic care. The launch of "Diprifusor" as the first commercially available TCI system for propofol was the cornerstone of a successful research period within the last decade, which evaluated the pharmacokinetic foundations of computer assisted intravenous drug delivery. We are now in a period where TCI technology is becoming a part of routine anaesthesia technique for the practitioner rather than a research tool for specialists and enthusiasts. This review gives an update on the rational pharmacokinetic basis of TCI development, the preliminary clinical experience with the new technique, the performance and accuracy of TCI devices and potential technical pitfalls in clinical routine. Besides clinical application in anaesthesia with "Diprifusor" TCI, target controlled systems are expected to play a significant role as research tools in the evaluation of drug interactions in anaesthesia and in the development of novel control techniques for the administration of sedative and analgesic drugs in the peri-operative period.     

Bispectral index in patients with target-controlled or manually-controlled infusion of propofol

In this prospective, randomized study we compared bispectral index (BIS), hemodynamics, time to extubation, and the costs of target-controlled infusion (TCI) and manually-controlled infusion (MCI) of propofol. Forty patients undergoing first-time implantation of a cardioverter-defibrillator were included. Anesthesia was performed with remifentanil (0.2-0.3 micro g. kg(-1). min(-1)) and propofol. Propofol was used as TCI (plasma target concentration, 2.5-3.5 micro g/mL; n = 20) or MCI (3.0-4.0 mg. kg(-1). h(-1); n = 20). BIS, heart rate, and arterial blood pressure were measured at six data points: T1, before anesthesia; T2, after intubation; T3, after skin incision; T4, after first defibrillation; T5, after third defibrillation; and T6, after extubation. There were no significant hemodynamic differences between the two groups. BIS was significantly lower at T3 and T4 in the TCI group than in the MCI group. The mean dose of propofol was larger in TCI patients (5.8 +/- 1.4 mg. kg(-1). h(-1)) than in the MCI patients (3.7 +/- 0.6 mg. kg(-1). h(-1)) (P < 0.05), whereas doses of remifentanil did not differ. Time to extubation did not differ between the two groups (TCI, 13.7 +/- 5.3 min; MCI, 12.3 +/- 3.5 min). One patient in the MCI group had signs of intraoperative awareness without explicit memory after first defibrillation (BIS before shock, 49; after shock, 83). Costs were significantly less in the MCI group (34.83 US dollars) than in the TCI group (39.73 US dollars). BIS failed to predict the adequacy of anesthesia for the next painful stimulus. IMPLICATIONS: In this prospective, randomized study, bispectral index (BIS), hemodynamics, time to extubation, and costs of target-controlled infusion (TCI) and manually-controlled infusion of propofol were compared. TCI increased the amount of propofol used. BIS failed to predict the adequacy of anesthesia for the next painful stimulus.     

Target-controlled infusion anesthesia with propofol and remifentanil compared with manually controlled infusion anesthesia in mastoidectomy surgeries

Target-controlled infusion (TCI) system is increasingly used in anesthesia to control the concentration of selected drugs in the plasma or at the site of drug effect (effect-site). The performance of propofol TCI delivery when combined with remifentanil in patients undergoing elective surgeries has been investigated. Our aim in this study was to assess the anesthesia profile of the propofol and remifentanil target controlled infusion (TCI) anesthesia as compared to the manually controlled infusion (MCI), in mastoidectomy surgery, where a bloodless field is of utmost importance to the surgeon. Sixty patients, aged 18-60 years ASA I-II enrolled in the study, were divided into two equal groups. Group MCI received propofol and remifentanil by conventional-dose-weight infusion method, and Group TCI received propofol 4 microg/ml and remifentanil 4 ng/ml as effect-site target concentration. The hemodynamic variability, recovery profile, postoperative nausea and vomiting (PONV), surgeons satisfaction were assessed. Results were analyzed by SPSS version 11.5. The two groups were comparable with respect to age, ASA class, sex, weight, basal vital signs, operation time. The blood pressure and pulse were above desired levels in some data points in the MCI Group (P < or = 0.05). The PACU stay time to reach Aldret score of 10 was longer in the MCI Group (42.54 +/- 8 vs 59.01 +/- 6 min) (P < or = 0.05). The PONV was more common in the MCI Group (P < or = 0.05). Surgeon's satisfaction of the surgical field showed no significant differences except when described as "good", more common in the TCI Group. TCI is capable to induce and maintain anesthesia as well as MCI. In some stages of anesthesia, the TCI control of vital signs are better than the MCI. In some stages of anesthesia, the TCI control of vital signs are beter than the MCI. Recovery profile and complication rate and surgeon's satisfactions are more acceptable in the TCI than in the MCI Group.     

Remifentanil target-controlled infusion vs propofol target-controlled infusion for conscious sedation for awake fibreoptic intubation: a double-blinded randomized controlled trial

BACKGROUND: Awake fibreoptic intubation (AFOI) is a technique used in patients with difficult airways. This study compares the suitability of remifentanil target-controlled infusion (TCI) to propofol TCI for conscious sedation during AFOI in patients with bona fide difficult airways. METHODS: We recruited 24, ASA I-III patients, who were undergoing sedation for elective AFOI. Patients were randomized to one of the two groups, Group P (n=10) received propofol TCI and Group R (n=14) received remifentanil TCI. Primary outcome measures were conditions achieved at endoscopy, intubation, and post-intubation, which were graded using scoring systems. Other parameters measured were the endoscopy time, intubation time, and number of attempts at intubation. A postoperative interview was conducted to determine recall of events and level of patient satisfaction. RESULTS: Endoscopy scores (0-5) and intubation scores (0-5) were significantly different [Group P 3 (1-4) vs Group R 1 (0-3) P<0.0001, Group P 3 (2-4) vs Group R 1 (0-3) P<0.0001, respectively]; with much better conditions in Group R, endoscopy times and intubation times were also significantly different, being shorter in Group R (P<0.007 and P<0.023, respectively). Patient tolerance of the procedure, judged by the discomfort scores (P<0.004) and the post-intubation scores (P<0.08), was significantly better in Group R. The level of recall for events was higher in Group R. However, there were no significant differences in the patient satisfaction scores. CONCLUSIONS: Remifentanil TCI appears to provide better conditions for AFOI when compared with propofol TCI. The disadvantage of remifentanil in this setting may be a higher incidence of recall.     

ZURÜCKGEZOGEN: Propofolapplikationssysteme

Background

During anaesthesia propofol is administered either by manual controlled infusion (MCI) or by target controlled infusion (TCI) techniques. In this study two different TCI systems for propofol administration were evaluated with regard to handling, patient safety, and costs and compared to administration of propofol by the MCI technique.

Methods

In a prospective study, 90 patients scheduled for elective surgery of the nose or nasal sinuses were randomly enrolled in three groups. The two TCI systems were examined in two groups of 30 patients: one group received propofol following the pharmacokinetic TCI model of Schnider (TCI-Schnider) and the other group received propofol following the TCI model of Marsh (TCI-Marsh). A manual perfusion technique (MCI, n=30) was used in the control group. Depth of anesthesia was controlled using the bispectral index (BSI) which was adjusted to fall within the range of 40–55. Hemodynamics, extubation times and time of awaking, rate and quality of propofol dose adjustment, total drug requirements, costs, and quality of recovery were documented. The incidence of postoperative nausea and vomiting (PONV) as well as shivering and patient satisfaction were also documented.

Results

Demographics, hemodynamics and perioperative data did not differ between the groups. Propofol consumption within the first 60 min also showed no significant differences. In the course of extended anaesthesia, propofol consumption was significantly less in both TCI groups compared to the control group (MCI) and the TCI-Schnider group also showed less episodes of bradycardia. The necessity of propofol dose adjustment did not differ significantly between the TCI groups. Administration and consumption of anaesthesia co-medication (fentanyl, remifentanil, cisatracurium) did not differ between the groups.

Conclusion

The investigated propofol administration procedures using the MCI or TCI techniques were safe and easy to handle under BIS monitoring. No differences were found concerning extubation times and time of awaking. During extended anaesthesia procedures (>60 min), propofol consumption was lower with both TCI techniques and thus costs could be saved.     

Induction and maintenance of intravenous anaesthesia using target-controlled infusion systems

Total intravenous anaesthesia (TIVA) has several potential advantages: (i) each component of anaesthesia can be regulated independently and adapted to changes in the stimulus during surgery, (ii) lack of pollution, (iii) ease of use in ‘remote locations’, (iv) quality of recovery. The main drawback of TIVA is that it is difficult to use. Target-controlled infusion (TCI) is a new technique for the administration of intravenous agents based on real-time pharmacokinetic and pharmacodynamics simulations. Its aim is to control and maintain a steady therapeutic level of drugs with a narrow margin of safety. TCI is intended to be similar to the vaporizer of volatile anaesthetics. TCI has been used for more than 15 years for research purposes but the recent availability of a marketed system dedicated to propofol (Diprifusor) is a landmark in the dissemination of the technique. TCI can be used with other hypnotic drugs (midazolam, ketamine, etomidate) and also with opioids. Sedation and post-operative analgesia are also indications for TCI administration. TCI makes it possible to apply more easily certain tedious pharmacokinetic and pharmacodynamic concepts at the bedside at a low cost with potential clinical benefits for the patient. Clinical studies have demonstrated that TCI is as safe as manual infusion techniques but is preferred by anaesthesiologists because it reduces the workload. The main limit of this method at the present time is the large interindividual pharmacokinetic and pharmacodynamic variability and the lack of marketed systems for opioids. Population pharmacokinetics, effect compartment control and even closed-loop systems or Bayesian forecasting are possible directions for future improvements.     

Target-controlled infusion of propofol and remifentanil in cardiac anaesthesia: influence of age on predicted effect-site concentrations

Background. Propofol-anaesthesia administrated via target-controlledinfusion (TCI) has been proposed for cardiac surgery. Age-relatedchanges in pharmacology explain why propofol dose requirementis reduced in elderly patients. However, the Marsh pharmacokineticmodel incorporated in the Diprifusor propofol device does nottake age into account as a covariable. In the absence of depthof anaesthesia monitoring, this limitation could cause adversecardiovascular effects resulting from propofol overdose in olderpatients. We assessed the influence of age on effect-site propofolconcentrations predicted by the Diprifusor and titrated to thebispectral index score (BIS) during cardiac anaesthesia. Methods. Forty-five patients received propofol by Diprifusorand remifentanil by software including Minto model. Propofoland remifentanil effect-site concentrations were adapted toBIS (40–60) and haemodynamic profile, respectively. Theinfluence of age on effect-site concentrations was assessedby dividing patients into two groups: young (<65 yr) andelderly (     

Target controlled infusion (TCI): applications of the "TCI visual" program in anesthesia and sedation with propofol

BACKGROUND: Systems for Target Controlled Infusion accepting not only patient' data, like Diprifusor, but also a pharmacokinetic model have not been available in Italy in the last years. Therefore a program which controls a Pilot Anesthesia Vial pump and accepts any pharmacokinetic model was developed and applied to propofol infusion for anaesthesia and sedation. METHODS: Two versions of the Visual TCI program have been developed. The first, at intervals, supplies the anaesthetist with the values for the pump; the second directly interacts with the pump. The program also supplies the anaesthetist with the current amount of drug in each compartment and with the estimated awakening time. DESIGN: preliminary prospective study. SETTING: operatory theatre and Intensive Care Unit in a University Hospital. Patients: 6 patients undergoing total intravenous anaesthesia with propofol and fentanyl for abdominal surgery; 6 patients undergoing sedation with propofol in an Intensive Care Unit (the first 4-hour period was taken into account). Interventions: propofol infusion was regulated by the Visual TCI program. The first version was employed in three patients of each group and the second one in the others. Hypo- and hypertensive episodes (systolic pressure less than 80 mmHg or higher than basal value plus 25%) were recorded during anaesthesia and sedation. Propofol concentration was measured in plasma three times at defined intervals and per cent differences between measured and computer-calculated values (Predictive error, PE) were calculated. RESULTS: No hypo- or hypertensive episodes were recorded. PE was 27.4 +/- 17.9%. CONCLUSIONS: The program was easily employed, caused no inconvenience, and its use was associated with a remarkable cardiovascular stability. PE distribution was acceptable on the ground of the criteria reported in the literature. The program can be applied to drugs other than propofol, with both two and three compartment pharmacokinetic models and the anaesthetist can choose the most suitable model for the patient.     

Propofol formulated with long-/medium-chain triglycerides reduces the pain of injection by target controlled infusion

BACKGROUND: Propofol is a widely used intravenous anesthetic although its injection pain is a common and unpleasant problem. Long-/medium-chain triglyceride (LCT/MCT) propofol has been introduced, as its low free propofol content is expected to reduce injection pain compared with LCT propofol. Target controlled infusion (TCI) differs from conventional induction in the initial infusion pattern. During induction using TCI, we investigated injection pain caused by two propofol solutions with different triglyceride compositions. METHODS: Fifty patients, ASA I-II, with adequate communicative ability, were randomly assigned to two groups. TCI was conducted with Diprifusor for LCT and with BeComSim (custom-made software) for LCT/MCT. The target blood concentration was set at 4 microg/ml for both groups. At 30, 60, and 120 s after the infusion, patients were asked questions regarding the severity of pain on a 0-10 pain score. The total dose of propofol and the time required to induce anesthesia were also investigated. RESULTS: The LCT/MCT propofol group had a larger number of pain-free patients and showed lower severity of pain than the LCT group [the number of pain-free patients being 11 and 3, respectively (P < 0.05), and median maximum pain being 0 and 4.5, respectively (P < 0.01)]. The dose and time required for induction were not significantly different between the groups (dose of 84 +/- 27 and 80 +/- 24 mg, respectively, and time of 119 +/- 60 and 107 +/- 55 s, respectively). CONCLUSION: Our study showed that the frequency and severity of pain during TCI induction with propofol could be significantly reduced using LCT/MCT propofol rather than LCT propofol.     

Comparison of target-controlled infusion and manual infusion for propofol anaesthesia in children

Background

One major criticism of prolonged propofol-based total i.v. anaesthesia (TIVA) in children is the prolonged recovery time. As target-controlled infusion (TCI) obviates the need to manually calculate the infusion rate, the use of TCI may better match clinical requirements, reduce propofol dose, and shorten recovery time.

丙泊酚靶控输注全麻诱导时机体应激反应的临床研究

目的　观察丙泊酚靶控输注 (TCI)用于全麻诱导对皮质醇、血糖和心率变异性 (HRV)的影响。方法　 48例全麻插管病人随机分为两组 ,A组采用Diprifusor/TCI系统分六步诱导给药 ,B组人工推注丙泊酚。观察心率、血压、SpO2 、ECG、HRV ,并于诱导前 (T0 )、意识消失时 (T1)、插管时(T2 )、插管后 1min(T3 )、3min(T4 )、5min(T5)抽取静脉血检测血糖、皮质醇。结果　A组心率、DBP、SpO2 、血糖和皮质醇各时点无明显差异 ,HRV、SBP各时点较T0 明显降低 (P <0 0 5 ) ,但插管前后无明显差异 ;B组T1、T2 的心率、血压明显低于T0 和T3 、T4 、T5,也明显低于A组各时点 (P <0 0 5 ) ,T3 的HF、血糖、皮质醇明显高于T0 和其他各时点及A组 (P <0 0 5 ) ,而LF/HF明显低于T0 、T1和T5及A组 (P <0 0 5 )。结论　丙泊酚TCI用于全麻诱导插管时机体应激反应小 ,诱导过程中生命体征平稳。     

A comparison of target- and manually controlled infusion propofol and etomidate/desflurane anesthesia in elderly patients undergoing hip fracture surgery

Elderly patients have a higher risk of developing adverse drug reactions during anesthesia, especially anesthesia affecting cardiovascular performance. In this prospective randomized study we compared quality of induction, hemodynamics, and recovery in elderly patients scheduled for hip fracture surgery and receiving either etomidate/desflurane (ETO/DES) or target-controlled (TCI) or manually controlled (MAN) propofol infusion for anesthesia. Sixteen patients were anesthetized with ETO (0.4 mg/kg) followed by DES titrated from an initial end-tidal concentration of 2.5%. Eighteen patients received propofol TCI at an initial plasma concentration of 1 microg/mL and titrated upwards by 0.5-microg/mL steps. Fifteen patients received a bolus induction of propofol 1 mg/kg over 60 s followed by an infusion initially set at 5 mg . kg(-1) . h(-1). All received a bolus (20 microg/kg) followed by an infusion of 0.4 microg . kg(-1) . min(-1) alfentanil. According to hemodynamics, concentrations of DES or propofol (TCI group) and propofol infusion rate (MAN group) were respectively adjusted by a step of 20% and 50%. In the TCI and ETO/DES groups, the time spent at a mean arterial blood pressure within 15% and 30% of baseline values was more than 60% and 80% of anesthesia time, whereas in the MAN group it was <30% and 60%, respectively. In the MAN group more anesthetic drug adjustments were recorded (6.4 +/- 2.8 versus 2.5 +/- 1.2 [ETO/DES] and 2.6 +/- 1 [TCI]). TCI improves the time course of propofol's hemodynamic effects in elderly patients.     

子宫切除术后舒芬太尼病人自控-靶控镇痛的安全性和有效性

目的 评价子宫切除术后舒芬太尼病人自控.靶控镇痛(PCA-TCI)的安全性和有效性.方法 择期经腹子宫切除术病人60例,ASA I或Ⅱ级,年龄20-59岁,体重45-75 kg术毕采用视觉模拟评分法(VAS评分)评价疼痛程度,随机分为3组(n=20),I组VAS评分=0时进行PCA-TCI,初始血浆靶浓度为0.08 μg/L;Ⅱ组VAS评分≥2分时进行PCA-TCI,初始血浆靶浓度为0.08μg/L;Ⅲ组VAS评分≥2分时进行PCA-TCI,初始血浆靶浓度为0.1 μg/L;PCA锁定时间为6 min.于PCA-TCI启动前即刻(T0)和启动后1 h(T1)、2 h(T2)、4 h(T3)、8 h(T4)、16 h(T5)和24 h(T6)时,记录平均动脉压(MAP)、心率(HR)、脉搏血氧饱和度(SpO2)、呼吸频率(RR)、VAS评分和脑电双频谱指数(BIS).于T1～6时记录总按压次数(D1)和有效按压次数(D2).记录术后24 h内舒芬太尼用量和不良反应发生情况.结果 各组各时点HR、MAP、RR和SpO2均在正常范围内,BIS均大于85,组内和组间比较差异无统计学意义(P>0.05).与T0时比较,I组T1～6时VAS评分差异无统计学意义(P>0.05),Ⅱ组和Ⅲ组T1～6时VAS评分降低(P<0.05).与l组比较,Ⅱ组T0～2时和Ⅲ组T0.1时VAS评分升高,Ⅱ组术后0～2 h时和Ⅲ组术后0～1 h时D1和D2升高,Ⅱ组和Ⅲ组术后24 h内舒芬太尼用量升高(P<0.05).各组病人术后均未见心动过速、心动过缓、低血压、呼吸抑制和镇静过度等的发生.结论 子宫切除术后舒芬太尼PCA-TCI是安全、有效的,在术后疼痛尚未出现时进行PCA-TCI,且初始血浆靶浓度为0.08μg/L的镇痛效果更好.     

Target-controlled infusion of propofol induction with or without plasma concentration constraint in high-risk adult patients undergoing cardiac surgery

BACKGROUND: Calculated plasma (Cp) and calculated effect site concentrations (Ce) of propofol associated with loss of consciousness (LOC) have been studied in young healthy patients. The aim of the study was to evaluate the calculated propofol concentrations required to induce LOC in ASA III adult patients undergoing cardiac surgery using a smooth target controlled infusion of propofol. METHODS: After informed consent, 44 patients were premedicated with 0.5 mg alprazolam orally. Propofol TCI using the pharmacokinetic set of Marsh et al. incorporated in the Diprifusor (ThalfKeo of 2.6 min) was used. Propofol Ce was progressively increased by 0.5 micro g/ml until LOC was obtained. The constraint on the maximum gradient between Cp and Ce was either 1 micro g/ml in group 1 or not limited in group 2. Hemodynamic variations were assessed. RESULTS: Mean preoperative left ventricular ejection fractions were 44 +/- 15.4% and 56 +/- 11.4% in groups 1 and 2, respectively (P < 0.01). At LOC, mean Cp was 1.9 micro g/ml in both groups but mean Ce was 1.08 +/- 0.31 and 1.43 +/- 0.42 micro g/ml in groups 1 and 2, respectively (P < 0.01). The mean induction time was 12.8 +/- 7.1 min in group 1 and 8.5 +/- 2.7 min in group 2 (P < 0.05). No episode of hypotension has been observed in either group. CONCLUSION: In ASA III patients undergoing cardiac surgery, smooth propofol TCI induction, using the pharmacokinetic set of Marsh et al. incorporated in the Diprifusor, is associated with LOC at a low mean calculated plasma concentration of 1.9 micro g/ml and good hemodynamic stability.     

Propofol effective concentration 50 and its relationship to bispectral index

Sixty unpremedicated healthy adult patients were studied during induction of anaesthesia with intravenous propofol delivered by a 'Diprifusor' target-controlled infusion. Bispectral index (BIS) and spectral edge frequency (SEF95) were measured concurrently with the predicted blood and effect site propofol concentrations. Logistic regression was used to calculate the predicted propofol blood and effect site concentrations required to produce unconsciousness and no response to a noxious stimulus in 50% and 95% of patients and to correlate BIS with these end-points. The Diprifusor TCI software produces anaesthesia at consistent target concentrations. Bispectral index correlates well with clinical end-points and may be useful during propofol anaesthesia.     

Target controlled infusion: TCI

Progress in computing technology has allowed the development of target controlled infusion devices, with drugs delivered to achieve specific predicted target blood drug concentrations. Target controlled infusion (TCI) system has been developed as a standardised infusion system for the administration of opioids, propofol and other anaesthetics by target controlled infusion. A set of pharmacokinetic parameters has been selected using computer simulation of a known infusion scheme. The selected model is incorporated into a computer-compatible infusion pump. Clinical trials with such systems have provided appropriate target concentrations for the administration of target controlled infusion of anaesthetic drugs. The technique of TCI strongly influences the development of intravenous anaesthesia and opens a scenario of new and exciting applications in peri-operative anaesthetic management. The launch of 'Diprifusor' as the first commercially available TCI system for propofol was the cornerstone of a successful research period within the last decade, which evaluated the pharmacokinetic foundations of computer assisted intravenous drug delivery. Nowadays TCI technology is becoming a part of routine anaesthesia technique for the practitioner rather than a research tool for specialists and those who are enthusiasts of intravenous anaesthesia. Besides clinical application in anaesthesia, target controlled systems will play a significant role as research tools in the evaluation of drug interactions in anaesthesia and in the development of new control techniques for the administration of sedative and analgesic drugs in the peri-operative period.